The invention relates generally to speech recognition, and more specifically, to distributed speech recognition between a wireless device, a communication server, and a wireless local area network.
With the growth of speech recognition capabilities, there is a corresponding increase in the number of applications and uses for speech recognition. Different types of speech recognition applications and systems have been developed, based upon the location of the speech recognition engine with respect to the user. One such example is an embedded speech recognition engine, otherwise known as a local speech recognition engine, such as SpeechToGo speech recognition engine sold by SpeechWorks International, Inc., 695 Atlantic Avenue, Boston, Mass. 02111. Another type of speech recognition engine is a network-based speech recognition engine, such as SpeechWorks 6, as sold by SpeechWorks International, Inc., 695 Atlantic Avenue, Boston, Mass. 02111.
Embedded or local speech recognition engines provide the added benefit of speed in recognizing a speech input, wherein a speech input includes any type of audible or audio-based input. One of the drawbacks of embedded or local speech recognition engines is that these engines typically contain a limited vocabulary. Due to memory limitations and system processing requirements, in conjunction with power consumption limitations, embedded or local speech recognition engines are limited to providing recognition to only a fraction of the speech inputs which would be recognizable by a network-based speech recognition engine.
Network-based speech recognition engines provide the added benefit of an increased vocabulary, based on the elimination of memory and processing restrictions. Although a downside is the added latency between when a user provides a speech input and when the speech input may be recognized, and furthermore provided back to the end user for confirmation of recognition. In a typical speech recognition system, the user provides the speech input and the speech input is thereupon provided to a server across a communication path, whereupon it may then be recognized. Extra latency is incurred in not only transmitting the speech input to the network-based speech recognition engine, but also transmitting the recognized speech input, or N-best list back to the user.
Moreover, with the growth of wireless local area networks (WLAN), such as Bluetooth or IEEE802.11 family of networks, there is an increased demand in providing a user the ability to utilize the WLAN and services disposed thereon, as opposed to services which may be accessible through a standard cellular network connection. WLANs provide, among other things, the benefit of improved communication speed through the increased amount of available bandwidth for transmitting information.
One current drawback to speech recognition are limitations of recognition caused by factors, such as, an individual user's speech patterns, external noise, transmission noise, vocabulary coverage of the speech recognition system, or speech input beyond a recognition engine's capabilities. It is possible to provide a speech recognition engine which is adaptable or predisposed to a specific type of interference, such as excess noise. For example, a speech recognition engine may be preprogrammed to attempt to recognize speech input where the speech input is provided in a noisy environment, such as an airport. Thereupon, a user may provide the speech input while within an airport and if the speech input is provided to the specific speech recognition engine, the speech recognition engine may have a higher probability of correctly recognizing the specific term, based on an expected noise factor, typically background noise associated with an airport or an echoing or hollowing effect, which may be generated by the openness of terminal hallways.
Furthermore, simply because a WLAN may provide a specific service, an end user may not necessarily wish to utilize the specific service, for example, a user may have a subscription agreement with a cellular service provider and may incur further toll charges for utilizing a WLAN, therefore the user may wish to avoid excess charges and use the services already within the user's subscription agreement.